As shown in FIG. 6, the multi-head multi-needle sewing machine system of this type conventionally comprises a plurality of sewing machines 100A arranged in a line, each including a guide rail 102 for guiding a horizontal movement of a needle-bar support frame 101 and a positioning member 104 for guiding needle thread take-ups 103 at rest (see, for example, Japanese Examined Patent Publication Nos. 59(1984)-34386 and 53(1978)-48135). Particularly, the positioning member 104 must have a length W1, W2, W3 of about twice the horizontal length of the needle-bar support frame 101, such that with a far-left needle thread take-up 105L set at a sewing position X, a far-right needle thread take-up 105R may not disengage from the positioning member 104, and vise versa.
Accordingly, the prior-art multi-head multi-needle sewing machine system detrimentally has a great horizontal length because a distance between adjacent sewing machines 100A is about twice the horizontal length of the needle-bar support frame, as seen in the figure. Hence, the conventional multi-head multi-needle sewing machine system cannot accomplish space savings in a sewing plant. Additionally, there has been an obstacle to further increasing the number of sewing heads mounted to the sewing machine system. More recently, a strong demand exists for the use of an even greater number of colors of threads. However, with increase in the number of colors of threads, the greater number of needles must be employed, which results in an increased size of the needle-bar support frame. This further requires the increase in the distance between adjacent sewing heads, naturally resulting in a reduced number of sewing heads mounted to the system. Consequently, a significant reduction of efficiency cannot be avoided.